The present invention relates to an articulated lever arrangement for transmitting limited tilting motions with alternating direction with at least one pivot and one lever provided with a bearing opening for the pivot.
Lever arrangements of this type are a component of many technical devices and are used, for instance, in low-voltage circuit breakers for transmitting forces to the contact members. As long as the forces are small, parts with the simplest design are sufficient to meet the intended purpose. If, however, the forces are larger and if the motions are executed with very high acceleration, considerable mechanical problems can be expected. It therefore presents difficulties, even if the parts are designed strong and carefully, to keep the wear so small that a specified number of operation cycles is possible. This problem applies, for instance, in low-voltage circuit breakers, e.g., according to U.S. Pat. Nos. 3,301,984 or 3,849,619 to the joint between a thrust lever transmitting the force of a spring accumulator, a driver lever mounted on a control shaft and to a coupling organ transmitting the motion to a contact arrangement, since at this point, not only the actuating energy leading to a contact member is passed-on in the case of multi-pole circuit breakers, but also the actuating energy for further contact members connected to the control shaft.
In mechanical engineering, various designs and components are known per se which are suitable for the low-wear and low-friction transmission of large forces under unfavorable conditions. Lever arrangements of such design, however, require a larger amount of space which cannot be made available in view of the extremely compact design of modern circuit breakers. Also lubricating the lever arrangements turned out to be a problem because the lubricants cannot be brought to bear in the desired manner due to design conditions. If oil-like lubricants are chosen, for example, they wet the bearing surfaces due to their creep behavior, and protect the bearings insufficiently because of the limited toughness and load-carrying capacity of the lubricant. In addition, there is the danger, because of the jerky motions with high acceleration as they occur in circuit breakers, that oil-like lubricants are flung from the parts to be lubricated and cause undesired soiling in the interior of the circuit breaker. If, on the other hand, lubricants with a greasy or fatty constitution are chosen, i.e., with greater viscosity, they are effective only for a few operating cycles because the lubricant is then displaced and used up and cannot flow back due to its great viscosity.